Recycled PET plastic bottles are frequently used in the drink industry for producing new plastic bottles. For this purpose, the recycled old bottles are first shredded and then foreign particles, for example, particles of foreign plastics such as PVC, are sorted out from the ground material flow gained in this way. The PET particles or PET flakes obtained in this way are then used to manufacture new PET bottles.
During the sorting out process, large foreign substance particles can be separated out by means of an optical sorter or NIR sorter (near-infrared sorter). The ground material flow normally also comprises small foreign particles, however, which are not detected by the optical or NIR sorter. These fine particles can crystallize out during the further processing and so cloud the plastic bottles manufactured from the recycled material.